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THOUGHTS 


ON 


OUR  CONCEPTIONS 


OF 


PHYSICAL  LAW 

'.I 


BY  ii  /j 

PROF.  FRANCIS^^Ev  OTRt^]^R.  ^^'  fy, 


''<'vr. 


An  address    hkfork   thf,  Ai.rMNi  ok   i'iik   State    University  of    Iowa,  June  19,    j 
1878;   Di'.i.ixERicD  A 1'   Kansas  C'liv,   Decemijer  23.    1878. 


PRINTED  AT  THE  OFFICE  OF  THE  KANSAS  CITY  REVIEW. 


LIBUAU 

UNIVEH8.  .  , 


i^lA.  I 


Thoughts  of  Our  Conceptions 


-OF- 


PHYSICAL  LAW. 


BY    PROF.     FRANCIS    E.    NIPHER,   ST,    LOUIS,     MO. 


All    addcr.ss  'ucforc  the  Alumni  of  the  State    University  of  Iowa,  June  lUih,  1878;  delivered  at  Kan.^as 

City,  December  23d,  1878. 

In  the  short  time  at  my  disposal,  I  wish  to  point  out  some  reasons  for  the 
more  general  cultivation  of  a  certain  cardinal  virtue  which  is  so  rare  that  I  fear 
it  has  no  name.  Perhaps  the  words,  Intellectual  Modesty,  would  come  as  near  as 
any  others  in  expressing  what  I  mean.  The  world  is  very  full  of  people  who  are 
ready  to  make  assertions  upon  subjects  which  are  evidently  too  difficult  for  them 
— in  many  cases  too  difficult  for  any  one— to  handle  with  any  degree  of  cer- 
tainty ;  and  it  doubtless  often  happens  that  some  who  have  meditated  studiously 
for  years  upon  some  such  subject,  arriving  at  no  satisfactory  conclusion,  are 
regarded  as  objects  of  profound  commiseration  by  others,  who  rush  upon  conclu- 
sions like  the  unthinking  horse  into  the  battle.  It  is  as  natural  that  people  should 
thus  differ,  as  that  some  should  have  darker  skins,  taller  frames,  or  more 
irritable  tempers  than  others.  To  what  extent  these,  and  other  differences  which 
we  shall  point  out,  are  blameworthy,  we  cannot  attempt  to  discuss,  but  shall 
study  the  mental  habits  of  men  in  precisely  the  same  spirit  in  which  we  would 
study  the  habits  of  other  animals.  But  I  wish  to  show  some  tangible  reasons  for 
thinking  that  there  are  very  few  subjects  upon  which  we  can  dogmatize,  and  that 
in  any  case  it  is  unnecessary.  I  wish  to  advocate  the  cultivation  of  intellectual 
modesty,  not  merely  because  it  seems  to  me  to  be  one  of  the  brightest  ornaments 
of  the  human  mind,  but  because  of  its  vital  connection  with  another  cardinal 
virtue — intellectual  honesty. 

Perhaps  this  end  will  be  best  attained  by  considering  the  difficulties   which 


2  THOUGHTS  ON  OUR  CONCEPTION  OF  PHYSICAL  LAW, 

are  met  in  the  investigation  of  any  subject,  when  the  sole  aim  is  to  find  out  the 
truth  of  the  matter,  and  I  have  thought  it  proper  to  point  out  some  of  the  diffi- 
culties to  which  we  are  subject  in  arriving  at  our  conceptions  of  physical  law. 

The  study  of  physical  science  has  endowed  the  human  mind  with  an  attribute 
which  is  usually  ascribed  to  and  is  thought  to  be  characteristic  of  the  Divine 
Mind.  I  refer  to  the  power  of  prophecy.  The  astronomer  can  predict  the  posi- 
tion of  the  planets  for  generations  to  come,  basing  his  predictions  on  the  assump- 
tion— an  unproved  assumption — that  only  those  causes  which  he  has  considered 
will  act  in  the  future,  or,  in  other  words,  that  the  present  order  of  things  will  con- 
tinue. His  power  of  prediction  does  not,  however,  extend  indefinitely  into  the 
future,  for  there  are,  doubtless,  many  minor  disturbances  or  perturbations,  too 
small  to  be  detected  by  the  instruments  which  he  can  command,  without  many 
centuries  of  observation,  the  effects  of  which  will  become  plainly  apparent  after 
the  lapse  of  ages — that  is  to  say,  his  power  of  prophecy  is  limited  by  his  ignorance 
of  certain  facts,  and,  possibly,  by  his  inability  to  solve  the  equations  involved  in 
a  complete  discussion  of  the  subject. 

It  is  for  precisely  the  same  reason  that  we  cannot  foretell  the  future  destiny  of 
every  person  in  the  world.  But  to  a  m^nd  possessing  all  knowledge,  and  of  infinite 
power,  the  one  problem  would  evidently  be  as  simple  as  the  other. 

We  can  readily  imagine  a  being,  possessing  sufficient  knowledge  and  ability, 
to  calculate  the  orbits  of  every  person  now  living.  Such  a  being  must  know  all 
that  is  to  be  known  in  regard  to  our  mental  and  physical  organisms,  and  the  cir- 
cumstances under  which  we  are  and  will  be  placed.  Having  thus  the  initial  stage 
and  being  able  to  trace  succeeding  events  as  logical  sequences  of  the  present, 
such  a  being  could  predict  exactly  what  each  of  us  tvill  decide  to  do,  under  the  presefit 
and  all  succeeding  circumstances — could  predict  how  far  we  will  be  physically  and  men- 
tally able  to  carry  our  resolutions  into  effect. 

But  how  awful  must  be  the  mind  which  could  perform  such  a  task !  The 
most  gifted  mathematicians,  have,  after  enormous  labor  for  two  centuries,  given 
an  approximate  solution  of  the  interaction  of  three  gravitating  bodies,  but  they 
tell  us  that  the  methods  used  would  not  apply  to  four  bodies,  each  of  which  exerted 
appreciable  effects  upon  the  others.  How  utterly  beyond  human  power  it  would 
be  to  discuss  the  motions  of  the  millions  of  chemical  atoms  contained  in  a  single 
ounce  of  matter.  Herschel  has  said  that  each  of  these  particles  is  forever  solving 
differential  equations,  which,  if  written  out,  might  belt  the  earth. 

But  our  imagined  ideal  mind  must  deal  with  the  physics  of  our  globe,  and 
the  interaction  of  its  myriads  of  men.  The  whole  phenomena  of  meteorology 
must  be  calculated,  not  only  for  every  part  of  the  earth,  but  for  all  time.  The 
effect  of  these  climatic  influences  upon  each  man,  and  upon  the  grain  or  other  pro- 
ductions of  his  industry,  must  be  determined.  The  repressing  effects  of  political 
and  social  tyranny,  and  the  conditions  of  their  existence  ;  the  refreshing  effects  of 
food  and  sleep,  and  the  circumstances  which  may  sometimes  prevent  communi- 
ties or  individuals  from  obtaining  enough  of  them  ;  the  moral  influence  of  men 
upon  each  other — to  come  to  smaller  matters,  the  effect  of  the  present  address  up- 


THOUGHTS  ON  OUR  CONCEPTIONS  OF  PHYSICAL  LAW.  3 

on  each  member  of  the  present  audience — all  must  be  taken  into  account  [in  this 
stupendous  calculation.  And  now,  given  the  myriads  of  vibrating  atoms,  and 
whatever  else  may  constitute  a  man,  and  the  external  forces  which  act  upon  him, 
the  manner  in  which  the  atomic  motions  of  his  body  will  be  modified,  and  the  re- 
sulting effect  upon  his  thoughts  and  decisions  must  be  determined.  The  calcula- 
tion must  be  comprehensive  enough  to  include  the  thoughts  and  actions  of  all  men 
through  all  time.  Such  a  being  would  be  able  to  determine,  by  aid  of  some  high 
order  of  mathematical  analysis,  how  many  men  will  exist  upon  this  earth  five 
hundred  years  hence,  would  be  able  to  locate  each  man,  as  astronomers  predict 
the  position  of  planets,  and  must  be  able  to  predict  what  task  will  then  employ 
his  hands,  what  train  of  thought,  will  then  be  passing  through  his  mind.  A  great 
famine  occurs  in  China :  it  is  produced  by  a  combination  of  unfortunate  circum- 
stances, and  the  exact  limit  of  its  ravages  could  have  been  predicted,  ages  before. 

A  certain  closed  line  drawn  upon  the  earth,  would  mark  out  the  area  where 
25  per  cent,  of  the  inhabitants  would  starve  to  death.  Outside  of  this  area  would 
lie  a  belt  of  country,  where  20  per  cent,  would  die,  and  in  this  manner  the  whole 
of  the  melancholy  facts  could  be  represented.  The  discussion  of  the  distribution 
of  people  and  food,  the  means  of  transportation,  the  physical  strength  and  wealth  of 
individuals  affected,and  other  matters  involved  in  the  question,would  enable  an  all- 
powerful  mind  to  determine  to  what  extent  each  ^individual  would  be  affected  and 
which  ones  would  be  strained  beyond  physical  endurance.  The  position  of  each 
atom  of  matter  in  our  world  must  be  deducible,  and  the  exact  manner  in  which 
each  atom  moves  and  vibrates.  Some  portion  of  matter  may  repose  for  ages, 
locked  in  some  rocky  ledge.  Infinite  intelligence  can  calculate  when  a  chance 
stroke  from  a  workman's  hammer  may  beat  it  loose,  at  what  time  it  will  be  borne 
aloft  on  the  fickle  and  inconstant  winds,  and  when  and  where  it  will  again  fall, 
now  it  becomes  part  of  some  animal  or  plant,  but  everywhere  its  existence  is  rec- 
ognized and  its  path  is  traced  by  infinite  mental  power. 

When  we  consider  that  our  earth  is  but  a  speck  in  this  universe  of  universes, 
that  untold  millions  of  suns  and  worlds  are  scattered  through  space,  and  that  all 
are  grasped  by  a  knowledge  equally  profound,  we  begin  to  get  some  faint  idea  of 
the  magnitude  of  that  mind  which  can  solve  the  general  equations  of  the  universe, 
and  we  can  begin  to  reaHze,  how  comparatively  insignificant,  how  necessarily  im- 
perfect, are  our  highest  mental  achievements. 

Whether  or  not  there  be  such  a  being  as  the  one  we  have  here  imagined,  it 
would  be  foreign  to  our  purpose  to  discuss,  but  it  seems  to  me  that  very  few  who 
talk  fluently  on  either  side  of  the  question,  have  ever  tried  to  weigh,  in  a  calm  and 
dispassionate  manner,  the  awful  import  of  the  words  they  use. 

In  such  a  calculation  as  the  one  we  have  here  supposed,  mental  philosophy 
would  become  an  exact  science.  The  intensity  of  mental  action,  the  strength  of 
different  minds,  and  quantities  of  pleasure  and  pain  would  be  determined.  The 
logic  of  the  wise  and  the  foolish,  the  learned  and  the  ignorant,  the  virtuous  and 
the  vicious,  would  be  followed  out  to  the  conclusions  which  these  minds  would 
severally  reach,  under  the  particular  circumstances  in  which  each  is  placed. 


4  THOUGHTS  ON  OUR  COATCEPT/OXS  OF  PHYSICAL  LAW. 

Let  us  assume  that  one  of  the  secret  springs  of  human  action  is  this :  that 
any  given  case  we  decide  to  do  that  which  we  then  think  will  give  us,  on  t 
whole,  most  pleasure  or  least  pain,  often  deciding,  however,  to  give  up  a  greal 
pleasure,  to  be  enjoyed  only  in  the  future,  for  a  lesser  one  which  we  can  enj 
immediately,  precisely  as  we  sometimes  allow  a  note  to  be  discounted  in  ord 
that  we  may  realize  upon  it  at  once  ;  or,  to  take  another  case  :  we  have  in  mecha 
ics  a  principle  known  as  the  "  principle  of  least  action."  Applied  to  the  sol 
system,  it  affirms  that  each  of  the  planetary  bodies  so  moves,  that  the  sum  of  t 
energy  lost  by  counter  attraction,  is  less  than  if  they  moved  in  any  other  way. 
this  law  holds  in  the  interaction  of  men  in  society,  it  would  mean,  that  howev 
erratic  the  orbits  of  individual  men  may  be,  however  much  trouble  may  cor 
upon  them,  or  however[much  they  may  bring  upon  themselves,  taking  men  as  th^ 
are,  the  sum  of  human  trouble  is  less  than  if  men  did  differently,  being  what  th( 
are.  Assuming  that  man  is  wisely  constructed,  mentally  and  physically,  this 
merely  saying,  in  other  words,  that  the  present  order  of  things  is  a  wise  one. 

We  are  hardly  in  a  position  to  assert  that  either  of  these  statements  is  really 
law  of  social  physics.  They  are  referred  to  here  merely  to  indicate  the  natu; 
of  the  results,  which  could  be  reached  by  mathematical  analysis  if  we  were  able  t 
discuss  the  interaction  of  moral  and  mental  centers  of  action  as  astronomers  di 
cuss,  approximately,  the  interaction  of  worlds. 

Not  only  are  we  unable  to  predict  for  an  infinite  future,  on  account  of  tl 
summing  up  of  disturbances  which  cannot  be  detected  in  a  short  time,  with  oi 
means  of  investigation,  but,  as  before  suggested,  events  wholly  unexpected  to  oi 
partially  instructed  minds — apparent  breaches  of  continuity-^are  liable  to  happe 
at  any  time.  A  tribe  of  savages,  not  acquainted  with  fire-arms,  may  acquire 
loaded  musket.  In  toying  with  it  for  a  time  they  become  famifiar  with  its  appea 
ance,  and,  as  they  think,  with  its  properties.  But  some  day  they  succeed  in  di 
charging  it,  an  event  which  they  are  powerless  to  bring  about  again  by  an  exa< 
repetition  of  the  act  which  brought  it  about  before.  Who  shall  say  that  there  ai 
not  hair  triggers  in  the  universe,  upon  which  we  may  sometime  stumble  ?  ^-"  W 
can  imagine  intelligent  beings  living  on  a  world  surrounded  by  an  atmosphere  ( 
oxygen  and  hydrogen.  So  long  as  they  were  unacquainted  with  fire,  they  migl 
live  for  ages  in  fancied  security,"  studying  the  laws  of  the  evolution  of  their  work 
and  making  wise  predictions  in  regard  to  its  future.  But  the  production  of  a  sir 
gl«  spark  of  fire  would  ignite  their  atmosphere,  and  wrap  them  in  utter  destru( 
tion.  "■  We  know  not  at  what  moment  immense,  and  to  us,  wholly  unexpecte 
energies  may  be  called  into  action.  Por  all  that  our  knowledge  can  tell,  the  vo 
ume  of  human  history  may  be  finished  during  the  next  hour.  A  great  explosio 
on  the  sun  may  scorch  us  into  cinders  in  a  second.  The  earth  may  be  dashec 
to  pieces  and  dissipated  into  gas,  by  collision  with  some  immense  meteorite 
We  may  become  involved  in  a  nebulous  atmosphere  of  combustible  gas,  whici 
would  ignite  a  moment  later ;  in  fact,  as  was  so  eloquently  pointed  out  by  Mr 
Babbage,  there  is  no  catastrophe  too  great,  or  too  sudden,  to  be  consistent  witli 
the  reign  of  law,  and  the  continuity  of  action." 

*  bee  J  even's  Principles  of  Science,  1877.    pp.  742-748. 


THOUGHTS  ON  OUR  CONCEPTIOiYS  OF  PHYSICAL  LAW.  5 

In  the  discussion  of  physical  phenomena,  we  always  ignore  the  greater  part 
of  the  discussion,  by  neglecting  those  elements  which  are,  or  are  supposed  to  be, 
unimportant.  In  so  simple  an  operation  as  the  weighing  of  a  quantity  of  matter 
on  a  steelyard,  we  can  discuss  only  the  merest  elements  of  the  case.  The  stu- 
dent of  Physics  would  tell  you,  that  the  weights  are  inversely  as  the  lever  arms, 
])ut  this  is  far  from  being  the  whole  story.  During  the  weighing,  certain  parts  of 
the  steel  bar  are  heated;  other  parts  are  cooled;  still  other  parts  retain  their 
temperature  unchanged ;  electrical  currents  are  set  up  within  its  mass  ;  its  mag- 
netism is  changed;  its  torsion  and  elasticity  become  different — in  fact,  to  discuss 
all  the  changes  occurring  within  the  bar  during  so  simple  an  operation,  would 
infinitely  transcend  the  power  of  the  most  gifted  men. 

If  we  could  discuss  completely  the  laws  which  govern  phenomena,  we  should 
find  them  represented,  in  many  cases,  not  by  the  comparatively  simple  formulae, 
which  have  been  found  sufiicient  for  practical  purposes,  but  by  infinite  series,  the 
first  terms  only  of  which  our  mathematicians  have  been  able  to  deduce,  and  our 
physicists  to  experimentally  detect. 

What  is  here  said  of  physical  problems,  is  also  true  of  problems  of  pure 
mathematics.  It  is  stated  by  mathematicians,  "  that  those  problems  which  have 
been  solved,  are  but  an  infinitely  small  part  of  those  which  can  be  proposed,  that 
they  are  all  special  cases,  (although  sometimes  called  general)  and  that  if  a  prob- 
lem were  selected,  at  random,  out  of  the  whole  number  that  might  be  proposed, 
the  probability  would  be  infinitely  slight — that  any  human  being  could  solve  it." 
Even  those  problems  that  have  been  satisfactorily  solved,  involve  ideas  that 
we  cannot  comprehend.  Let  us  take  a  simple  problem  in  Geometry.  Imagine 
two  wooden  rods,  or  finite  lines  intersecting  each  other,  and  let  us  revolve  one  of 
them  until  they  become  parallel.  Consider  these  lines  infinitely  prolonged,  and 
let  us  see  what  becomes  of  these  prolongations.  As  one  line  is  revolved  the 
point  of  intersection  travels  outwards.  Finally  the  lines  might  seem  to  be  parallel, 
but  perhaps  if  we  were  to  travel  along  the  lines  for  a  million  of  miles,  we  might 
come  to  the  point  of  intersection.  The  mathematicians  say,  that  when  the  lines 
have  become  parallel,  the  point  of  intersection  will  be  removed  to  an  infinite 
distance,  which  is,  they  say,  equivalent  to  saying  that  the  lines  will  not  intersect. 
Where  in  space  will  these  lines  part  company  ?  Have  they  ends,  which  the 
point  of  intersection  finally  reaches,  and  which  then  separate  from  each  other? 
No  !  The  lines  are  supposed  to  be  without  end.  However  far  the  point  of  inter- 
section may  have  travelled,  we  may  straightway  regard  this  distance,  as  repre- 
sented by  the  first  term  of  a  divergent  series  of  an  infinite  number  of  terms, 
each  term  of  which  is  infinitely  greater  than  the  one  which  preceded  it.  We  can 
form  an  independent  conception  of  two  infinite  and  absolutely  parallel  lines, 
but  we  cannot  imagine  how  the  infinite  prolongations  of  intersecting  lines  can 
ever  separate;  nevertheless,  we  can  continue  the  rotation  of  our  finite  line, 
until  it  passes  through  parallelism,  and  the  point  or  at  least  a  point  of  intersection 
comes  travelling  towards  us  from  the  opposite  direction.  ^ 


6  THOUGHTS  ON  OUR  CONCEPTIONS  OF  PHYSICAL  LAW, 

Prof.  Jevons  appears  to  think  tl^at  our  difficulty  in  such  cases,  is  due  to  an 
imperfect  idea  of  infinite  space.* 

In  the  study  of  Physics,  our  most  certain  experimental  results  force  us  to 
ideas  equally  beyond  our  power  of  realization.  It  is  shown  beyond  question, 
that  light  moves  over  a  distance  of  about  seven  times  the  circumference  of  our 
earth  in  a  single  second.  We  must  look  for  something  marvelous  in  any  theory  \ 
which  can  account  for  so  marvelous  a  fact.  According  to  Newton's  theory,  we 
should  have  particles  of  light,  shooting  off  from  a  distant  luminous  body  with  j 
this  immense  velocity,  and,  falling  upon  a  mirror,  their  motion  would  not  merely 
be  checked,  but  the  elasticity  of  these  light  particles  must  be  assumed  to  be  so 
perfect,  that  they  rebound  with  an  equal  velocity. 

According  to  the  undulatory  theory,  the  light  consists  of  vibrations  of  a 
medium  which  fills  all  space.  Since  the  velocity  of  transmission  of  these  vibra- 
tions is  so  great,  it  follows  that  the  elasticity  of  this  medium  must  be  10,000,000,000 
times  as  great  as  that  of  the  hardest  steel.  Space  is  not  now  regarded  as  a  void, 
but  as  filled  with  a  medium  which,  as  Thomas  Young  remarked,  *'  is  not  only  highly 
elastic,  but  absolutely  solid."  And  yet,  as  we  walk  through  space,  the  solid 
atoms  which  compose  our  bodies,  experience  not  the  slightest  resistance.  Such 
ideas,  although  they  can  be  .conceived,  cannot  be  realized.  We  have  had 
no  previous  experience  with  materials  possessing  such  properties,  and  such  ideas 
must  necessarily  appear  strange  to  us ;  but  they  are  no  more  strange  than  the 
phenomena  of  light  which  we  directly  observe,  and  which  force  us  to  this,  or  to 
some  other  theory,  equally  marvelous.  Only  those  who  have  carefully  examined 
the  subject,  can  realize  how  weighty  is  the  evidence  in  favor  of  the  undulatory 
theory  of  light ;  but  where  such  stupenduous  conceptions  are  involved,  a  slavish 
acceptance  of  any  theory,  even  by  them,  would  be  in  the  highest  degree  objec- 
tionable.    We  are  not  the  friends  of  theories,  but  of  truth. 

So  in  all  departments  of  thought,  we  come  sooner  or  later  to  depths  which 
the  human  sounding  line  cannot  pierce  ;  we  reach  ideas,  about  which  it  becomes 
hazardous  to  talk,  unless  one  courts  the  position  of  a  babbler  of  nonsense;  we 
learn  that  all  our  "  final "  formulae  contain  unknown  quantities.  As  we  are 
not  infallible,  we  must  therefore  be  cautious  and  modest. 

It  is  not  surprising  then,  that  in  the  progress  of  our  sciences,  many  errors 
of  reasoning  and  in  the  interpretation  of  facts  have  been  committed.  You 
are  all  familiar  with  the  ideas  of  Newton,  in  regard  to  the  nature  of  light, 
ideas  which  were  not  in  themselves  absurd,  which  were  firmly  believed  in 
by  this  man  of  such  transcendent  power,  but  which  were  clearly  negatived  by 
results  of  subsequent  experiment. 

It  was  known  long  ago,  that  rain-gauges  placed  above  the  surface  of  the 
ground,  caught  less  rain  than  those  placed  at  the  surface,  and  it  is  still  taught  in 
many  of  our  text-books,  that  this  is  due  to  a  condensation  of  moisture  in  the 
lower  strata  of  the  atmosphere.  This  idea  is  not  absurd,  but  it  has  been  shown* 
that  this  cause  produces  no  appreciable  effect,  and  that  the  observed  effect  is  due 


*  Principles  of  Science,  p.  7C7 


THOUGHTS  ON  OUR  CONCEPTIONS  OF  PHYSICAL  LAW.  7 

the  action  of  the  wind,  *' which  sweeps   some  rain  out  of  all  gauges,  and  most, 
.11  of  those  which  are  highest,  and  therefore  most  exposed." 

Lavoisier's  idea  that  all  acids  were  compounds  of  oxygen,  received  a  com- 
pete refutation  when  the  constitution  of  prussic  and  muriatic  acids  became 
tiown.  In  fact,  the  errors  of  scientific  men  are  well  nigh  innumerable,  not  be- 
luse  they  are  men  of  science,  but  because  they  are  men^  and  we  are  probably 
istified  in  saying  quite  in  general,  that  if  the  man  who  never  committed  a  mental 
[under  be  found,  we  shall  also  find  a  man  who  never  conceived  a  vigorous 
lought.  The  fact  that  the  results  of  scientific  men  can  usually  be  checked  by 
bservation  and  experiment,  perhaps  diminishes  their  fiability  to  err  and  enables 
lem  to  discover  multitudes  of  errors  that  would  otherwise  escape  their  attention, 
'his  does  not  tend  to  make  the  results  of  their  investigations  less  weighty  than 
ssults  which  have  been  reached  by  other  processes,  more  purely  mental.  If 
len  of  science,  with  their  severe  methods  of  research,  their  habits  of  testing  their 
onclusions  by  observation  and  experiment,  are  nevertheless  led  into  wrong  con- 
usions,  what  does  it  prove  ?  Simply  that  the  human  mind,  even  under  the 
lost  favorable  circumstances,  is  fallible  !  Is  there  a  class  of  men  less  liable  to 
lake  mistakes  ?  It  is  precisely  this  experience  which  causes  many  to  place  a 
nail  value  upon  the  unsupported  assertions  and  speculations  of  any  man,  bow- 
lder honest,  earnest,  or  able  he  may  be. 

On  this  point,  one  of  the  most  admirable  of  experimenters,  Faraday,  has 
eautifully  said :  "The  world  little  knows  how  many  of  the  thoughts  and 
leories  which  have  passed  through  the  mind  of  the  scientific  investigator,  have 
een  crushed  in  silence  and  secrecy  by  his  own  severe  criticism  and  adverse 
xamination  ;  that  in  the  most  successful  instances,  not  a  tenth  of  the  suggestions, 
16  hopes,  the  wishes,  the  preliminary  conclusions,  have  been  realized." 

In  the  24th  series  of  his  "Experimental  Researches,"  Faraday  describes 
lany  tedious  and  intricate  experiments,  in  which  he  tried  to  connect  gravitation 
nd  electricity.  ' '  He  labored  with  characteristic  energy  for  days,  on  the  clock 
)wer  of  the  Houses  of  Parliament  and  in  the  shot-tower  of  Southwark,  raising 
id  lowering  heavy  weights,  connected  with  wire  coils.  Many  times  his  great 
till  as  an  experimenter  prevented  him  from  being  deceived  by  results  which 
thers  would  have  regarded  as  conclusive  proofs  of  his  idea,  and  when  the  whole 
as  done,  there  remained  absolutely  no  result."  For  although  the  results  were 
holly  negative,  Faraday  could  never  accept  them  as  conclusive  against  his  idea, 
)  which  he  had  been  led  by  his  experiments  on  the  relations  between  electricity 
nd  magnetism.  His  mental  condition  after  this  work  was  done,  is  best  described 
1  his  own  words.  "Occasionally,  and  frequently,  the  exercise  of  the  judgment 
ught  to  end  in  absolute  reservation.  It  may  be  very  distasteful,  and  great  fatigue 
>  suspend  a  conclusion;  but  as  we  are  not  infallible,  so  we  ought  to  be  cautious. " 

It  is  a  matter  of  common  observation, that  men  who,  like  Faraday,  have  done 
mch  to  widen  the  boundaries  of  our  knowledge,  are  precisely  the  ones  who  are 
lost  frequendy  in  a  state  of  doubt,  while  those    who   have   received  all  their 


Jevons,  xnPhil,  Mag.  Dec.  1861. 


8  THOUGHTS  ON  OUR  CONCEPTIONS  OF  PHYSICAL  LAW. 

knowledge  at  second  hand  are  generally  more  ready  with  a  positive  decision  and 
a  reason  for  it,  not  necessarily  because  their  intellectual  integrity  is  less,  but  be- 
cause they  cannot  realize  how  vain  a  thing  the  human  reason  is.  To  imagination 
and  reason,  controlled  and  checked  by  experiment  and  observation,  are  we  to 
look  as  the  source  of  the  greatest  advancement  in  science;  but  we  are  not  to 
look  for  infallibility,  and  in  cases  where  the  reason  alone  is  allowed  to  decide, 
where  observation  and  experiment  are  impossible,  the  uncertainty  must  necessa- 
rily be  greater.  In  many  cases  the  fact  that  the  subject  is  so  intrinsically  difficult 
that  no  experimental  check  is  possible,  appears  to  inspire  the  investigator  with  a 
confidence  in  his  conclusions,  that  could  hardly  be  reinforced  by  absolute  cer- 
tainty. 

But  we  have  not  yet  exhausted  the  list  of  errors  to  which  scientific  men  are 
liable,  in  arriving  at  what  we  provisionally  call  correct  conceptions  of  physical 
law.  A  few  of  them  have  carried  their  investigations  into  a  domain  in  which 
certain  hypothetical  beings  called  *' spirits"  are  said  to  be  the  main  actors.  It 
is  exceedingly  probable  that  a  few  trained  investigators  have  been  deceived  in 
regard  to  the  evidence  of  their  own  senses.  This  is  not  an»  unlooked  for  result, 
as  it  can  be  readily  reproduced  in  the  performances  of  any  expert  juggler. 

I  have  confined  myself  to  the  errors  which  scientific  men  have  committed, 
and  to  which  they  are  liable  in  their  search  for  truth,  not  because  they  alone  are 
liable  to  err,  but  because  a  discussion  of  the  multitude  of  errors  into  which  intel- 
lectual men  of  other  professions  have  fallen,  would  be  sure  to  give  offense.  But 
it  is  not  the  scientific  mind  which  stands  impeached — it  is  the  human  mind ! 

To  what  end  have  we  then  come  ?  It  appears  that  all  scientific  results  are 
attended  with  some  uncertainty.  Sometimes  the  uncertainty  is  very  small,  and 
we  are  able  to  obtain  a  numerical  estimate  of  it.  In  other  cases  it  may  be  possi- 
ble that  a  fundamental  misconception  of  the  truth  may  have  been  formed.  As 
an  instance  illustrating  what  I  mean,  we  may  cite  the  case  of  the  measurement  of 
the  Atlanta  base-line  by  the  engineers  of  the  United  States  Coast  Survey.  The 
whole  length  of  the  base-line  was  nearly  six  miles,  and  three  determinations  of  its 
length  showed  differences  of  about  3-10  of  an  inch — about  a  miUionth  of  the  entire 
length.  It  is  safe  to  say  that  if  these  re-measurements  had  shown  differences  of 
ten  feet,  there  would  have  been  no  quarreling  in  regard  to  which  measurement 
was  right,  but  all  would  have  been  rejected,  and  if  the  engineers  were  not  dis- 
missed as  incompetent,  they  would,  with  feelings  of  mortification,  have  begun 
their  work  over  again.  It  is  curious  to  observe  that  in  many  cases  \yhere  less 
skillful  men  attack  problems  infinitely  more  complex,  reaching  conclusions  differ- 
ing as  widely  as  the  poles,  we  have,  instead  of  conscientious  re-investigation, or  a 
modest  reservation  of  judgment,  dogmatic  discussions,  empty  words. 

In  the  other  case,  where  the  error  is  likely  to  be  a  fundamental  one,  the 
probability  of  the  truth  or  error  of  a  conclusion  cannot  always  be  determined 
numerically,  and  will  vary  greatly  in  different  minds.  Fur  instance,  A  may  think 
he  saw  a  ball  dropped  into  a  box,  and  may  feel  certain  that  it  is  yet  there;  B  is 
certain  that  it  was  a  juggler's  trick,  and  that  the  box  is  empty ;     C  did  not  see 


THOUGHTS  ON  OUR   CONCEPTIONS  OF  PHYSICAL  LAW.  9 

the  act,  and  has  no  opinion  in  the  matter.  About  \\it  fact  there  is  no  uncer- 
tainty :  the  ball  is  either  in  the  box  or  not.  No  discussion  can  affect  the  matter 
in  the  least.  The  uncertainty  is  purely  a  mental  affair,  its  degree  depending  upon 
the  ability  of  the  observers,  their  opportunities  for  investigation,  and  their  previ- 
ous training.  Their  differences  on  this  subject  will  be  wholly  obliterated  by  an 
exposure  of  the  interior  of  the  box,  and  without  the  necessity  for  any  discussion 
whatever.  If  the  box  cannot  be  opened,  the  matter  will  remain  a  legitimate  sub- 
ject for  dispute.  The  fact  that  competent  men  think  a  subject  worthy  of  dispute 
seems  to  me  a  good  indication  that  the  matter  is,  humanly  speaking,  uncertain. 
That  unpleasant  thing  called  intolerance,  in  those  cases  in  which  it  is  accom- 
panied with  sincerity,  arises  from  an  inability  to  see  these  points,  and  hence  we 
have  A  making  strenuous  efforts  to  convert  B  and  C  to  his  own  opinion,  failing  in 
which,  he  proceeds  to  burn  them,  to  imprison  them,  to  lampoon  them  in  the 
newspapers,  or  to  do  some  of  the  more  quiet,  but  scarcely  less  effective  things, 
characteristic  of  our  own  times,  that  the  spirit  of  the  age  will  permit.  Perhaps  no 
blame  is  to  be  attached  to  such  acts.  If  they  are  failings,  they  are  simply  to  be 
counted  in  with  the  other  failings  to  which  well  meaning  men  are  liable,  and 
when  the  evil  effects  fall  heavily  upon  us,  it  is  perhaps  wise  to  endure  them  with 
philosophic  calmness,  along  with  the  other  misfortunes  which  for  some  reason  or 
other  seem  incident  to  human  life. 

In  conclusion,  allow  me  to  say,  that  it  seems  quite  probable  that  human  wel- 
fare does  not  require  us  to  sit  in  judgment  on  the  ideas  of  others.  Thoughtful 
men  are  becomhig  more  and  more  impressed  with  the  vastness  of  the  unknown, 
and  the  comparative  insignificance  of  human  achievement,  while  the  demonstra- 
ted fallibility  of  human  reason  leads  them  to  temperance  and  modesty  of  thought 
and  expression ;  to  appreciation,  as  well  as  toleration,  of  opposition  and  doubt. 
•  Certain  it  is,  that  if  we  preserve  our  intellectual  integrity,  we  shall  be  unable  to 
settle  many  of  the  problems  that  interest  us  most.  If  we  decide  upon  some  of 
them,  and  other  persons  still  reserve  their  Judgment  or  decide  differently, we  need 
not  lose  our  tempers ;  they  have  not  only  decided  differently  from  us,  but  we 
have  also  decided  differently  from  them.  It  is  important  to  notice  that  neither  of 
these  decisions  has  affected  the  truth  in  the  least.  If  we  feel  called  upon  to  defend 
the  truth,  we  are,  after  all,  only  defending  ysi\idX\NQ  believe  lo  be  truth,  and  possibly 
against  men  as  honest  and  as  able  as  ourselves-  But  why  should  we  defend  the 
truth?  So  long  as  the  heart  of  humanity  shaU  pulsate,  will  not  truth  be  cherished 
there  ?  Why  would  it  not  be  far  better  for  each  one  to  put  himself  in  the  attitude 
of  a  reverent  searcher  iox  truth?  remembering  always,  that  the  little  decisions  that 
we  may  reach  are  possibly  wrong,  that  all  of  the  honesty  and  ability  in  the  world 
is  not  concentrated  within  ourselves,  and  the  comparatively  few  who  think  as  we 
do,  and  that  one  can  do  nothing  nobler,  than  to  make  himself  as  intelligent  and 
humane  as  possible,  resolutely  following  out  his  highest  convictions,  and  living 
at  peace  with  himself,  and  with  all  men. 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 
LOAN  DEPT. 

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